ShoeGuy: A New Slant on Pronation

The Biomechanical Theory Behind Orthotics

It's always nice when the readers write, especially a reader who’s right. And so it was when one Stacy Osborne, DPM, took keyboard in hand to respond to ShoeGuy’s answer to a question from the "Flowers & Flames" page in the September issue of this esteemed running publication.

"J.D. Denton’s answer to a reader’s question concerning orthotics is a little off base when he replied, ‘The orthotic itself doesn’t address the degree or velocity of over-pronation.’"

It’s nice that he accused me of only being "a little off base." Obviously, he’s never had a conversation with my brother-in-law, or he would know some consider me to be decidedly way off base.

"It has been demonstrated that running shoes and orthotics both can and do affect the rate or velocity of pronation."

The key word there is "both." Of course both shoes and orthotics work. Otherwise, why would millions of savvy runners invest so much time and credit card liability in both? ShoeGuy should have more clearly made his point by saying the orthotic "alone" doesn’t address the degree and velocity of over-pronation. Orthotics, amazing as they may be, need shoes that work with them.

The reader who started this mess, a Bruce Mihalick writing from cyber-land, simply wanted to know if he should continue to wear stability shoes with his new orthotics (as approved by his podiatrist), or could he now wear neutral shoes, assuming that the orthotics would do all of the correction needed.

My experience is that shoes used with orthotics should address the same issues said orthotics were designed to correct. An orthotic made to correct over-pronation, for example, is best supported in a shoe that does the same. Otherwise, both the foot and the orthotic may over-pronate together in a soft, flexible neutral shoe.

Doc Stacy, however, departed from the shoe-working-with-orthotic discussion and proceeded to do a mini-clinic on biomechanics:

"The human foot is designed to do five things when running: Make contact with the ground, absorb shock from the ground, adapt to the ground, lock onto the ground and propulse (sic) off the ground."

Sounds like a description on a Pentagon purchase order. There’s a lot going on down there, which is as good an excuse as any for those of us who run slowly. We’re just giving our feet enough time to contact, absorb, adapt, lock and propel.

"It has been my experience that the most common biomechanical fault that causes injuries is in phase two; if the runner’s foot spends too much time in the shock absorbing phase then every biological structure in the foot, ankle, shin, knee, thigh and hip has to work harder in phases three, four and five."

Wow. Your feet innocently screw up early on and all hell breaks loose for the rest of the time on the ground. No wonder running shoes have to work so hard.

"Couple that with over-training and under-resting…"

Not that any of us ever do that.

"…and you see all the over-use problems. Running shoes with motion control features help guide the foot through contact, shock absorption, adaptation, stance and propulsion at the correct time increment [so that] the stresses placed on that runner’s foot, leg and knee go down [as] does the risk of pain and injury."

Yep, and in some cases that would be running shoes with motion-control features AND a nifty pair of prescription orthotics inside, right Doc?

"Runners afflicted with chronic injuries who cannot find relief with the right shoe probably have the forefoot imbalance—forefoot varus. There currently are no shoes on the market for this."

Heck, with all the zillions of shoes out there, you’d think someone would work on that one. But no, it seems shoe designers are too busy trying to figure out new ways to whack away more support in the midfoot area of shoes. But, don’t get me started…

"Overpronators [with] a high forefoot varus need a biomechanical orthotic that alters the degree and velocity of pronation. This is accomplished by placing an extrinsic forefoot varus shim onto the orthotic's forefoot in order to trick the foot into thinking it’s down to the ground."

That would explain that layer of cork ShoeGuy sometimes sees bonded to the bottom of the foam covering of some orthotics, right behind the big toe and its neighbor. So, it’s really an extrinsic forefoot varus shim, designed to trick the foot.

Seems simple enough, but don’t go trying this on your own. A sports podiatrist, like our friend Stacy, is trained to know which feet need tricking and which don’t. And besides, it gives him something to do when he’s not writing letters.

"Think of orthotics as corrective ‘lenses’ for the feet."

Great quote, Stace. As one who has worn very powerful eyeglasses for many years, that makes sense. Maybe my eyes could use one of those extrinsic shim things.